import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String[] arr=sc.nextLine().split(" ");
        int flag=0;
        for(int i=0;i<arr.length;i++)
        {
            for(int j=0;j<arr.length;j++)
            {
                if(i==j)
                    break;
                if(arr[i].equals(arr[j]))
                {
                    System.out.println("yes");
                    flag=1;
                    break;
                }
            }
            if(flag==1)
                break;
        }
        if(flag==0)
            System.out.println("no");
    }
}
